The media conglomerate sues to overturn the recommendation of accountant-arbitrators, who say former shareholders of Harmonix were shafted.

After already paying $150 million to former shareholders of Harmonix, arbitrators have determined that Viacom owes an additional $383 million to the video game company that created Rock Band, according to a regulatory filing on Tuesday.

The revelation is the latest in an ongoing saga that began when Viacom purchased Harmonix for $175 million in 2006 plus promises that it would dish out bonuses based on sales of Rock Band, which was to be a way for the parent of MTV and VH1 to jump on the bandwagon started by Activision Blizzard and its Guitar Hero game.

Viacom, in fact, paid a $150 million bonus to Harmonix shareholders in 2007 but asked for most of that money back the next year because it claimed it wasn't making money on Rock Band. Harmonix shareholders responded with a lawsuit that sought $700 million in bonuses, in addition to the $150 million already paid.

Tuesday's filing says that "resolution accountants in the private dispute" determined Viacom should pay $383 million -- or $317 million less than what Harmonix shareholders were seeking -- though Viacom also says it filed a lawsuit Tuesday "seeking to compel the resolution accountants to consider arguments and evidence that were improperly excluded and to vacate the determination of the resolution accountants on the grounds of manifest error."

Published reports indicate that some 10 million units of Rock Band and its various spinoffs, including Beatles: Rock Band, have been sold, though hardware costs were so high that Viacom failed to turn the robust sales into profit. Viacom sold Harmonix, which is also behind the popular Dance Central video game, to investment firm Columbus Nova a year ago for $50 million.